2. :ij
- .., ·- ...-------...._
Give na1nes of the reagents to bring about the foll . ....__
transformations: owing
• & I ► # •
le 12.I
(i) Hexan-1-ol to hexanal (HJ Cyclohexanol to cyclohe
(iii) p-Fluorotoluene to (iv) Ethanenitrile to ethana1Xanone
p-fluorobenzaldehyde
Solution
lntext
(v) Ally! alcohol to propenal
(i) C5H5NH·cr03c1-(PCC)
(iii) Cr03
in the presence
ofacetic anhydride/
I. cr02c½ 2. HOH
(v) PCC
(vi)
(ii)
(iv)
(vi)
But-2-ene to ethanaI
Anhydrous CrO3
(Diisobutyl)aluminium
hydride (DIBAL-H)
O3
/H2
O-Zn dust
--
, 12.2 Write the structures ofproducts ofthe following reactions;
0
II
- /c,
+ C H CI
Anhyd. AIC13
2 5
(l)o
(iv)
.
J
3. Arrange the follO:ing compounds in the increasing order of their £xam le 12.2
botllng points:
CH3
CH2
CH.zCHO. CH3 CI-4CH2 CH20H. H5C2 -0 -C2H5 , CH3C~CH2 CH:,
TI1e molecular n1asses of these con1pounds are in the range of 72 to
. 74. Since only butan- 1-ol n1olecules are associated due to extensive
! tntcnnolecular hydrogen bonding. therefore. the boiling point of
; butan-1-ol would be the highest. Butanal is more polar than
· ethox-ycthane. Therefore. the intermolecular dipole-dipole attraction
is stronger in the former. n-Pentane molecules have only weak van
der W•al• forces. Hence increasing order of boiling points of the
gt,·en compow1ds is as follows: ;
1 CH_
,CHlCH'lCHl < H?iCZ-O-CZH5 < CH3Cf½CH2CHO < CH3CH2CH2CH20H
' - ...-..-...__.. __
_
.,.___~
Sol"tion
5. Would you expectbenzaldehyde to be more reactive or less reactivein ,
nucleophilic addition reactions than propanal? Explain your answer. ,
Solutiott The carbon atom of the carbonyl group of benzaldehyde is less
electrophilic than carbon atom of the carbonyl group present in ·.
co 6 propanal. The polarity ofthe carbonyl :
~ group is reduced in benzaldehydedue ;
'H to resonance as shown below and ·
< > H hence it is less reactive than propanal.
0tl
6. _,,_ •~,.. ....n._, _.._.,,..,- ._. ·• •
·· -~;.--,------- ---·· ~-··' ~-~· mpound (A) with 1nolt>-c ttlar fo nnul·i C 11
An
organic co · 1 o
d Prc
cipttatc Vith 2.4-DNP reagent nrld
~ " fon11,
orange-re •
0
tv ., a11
Solution
•
11 1
on )lcatlng with 1odlnc m t h e prcsenc" es y,11
preci~-~d
-a e It netther reduces Tollens· or Fchlings· rcag·e of sod1,ow,
hydro.'U e. B . e11t 11 urn
It ctecolourtse broJillnc watcr or a_cycr s 1-c'.1g~n t. On <lrast1~ o,or d
°" 1
with chromic acid. It gives a cai boi..-yllc a cid (Bl having 111 ><ldo11on :
,
1
'"'Ii o Identify the con1pounds (A) a n d (B) "lll d olecu1a_. ·
,onnu a '--
✓ u 2· • explain '
reactions 11wolved. lh,
(A) fomls
2
,4-DNP derivative. :11crcfore. it is an alrlchycle or a krt
Since It does not reduce Tollens or Fehling rea&
ren t. (A) musl be . k OJ1t
(A)
responds to 1odoform test. 'n1ereJorc. it s hould b e a meth ~
1
1
ketone. 1
d h h
Y t·ton ·
n,.e molecular formula of (Al In lcatcs lg degree of unsaturau '· j
it does not decolourtse bromine water or Baeyer·s reagent. ·n,tsln~;:;J'
1
i
the presence of w1saturaUon due to an aromatic rlng. "' j
con
1
pound (B). being an oxidation produc t of a kelone should bea :
c.arbo~-ylic acid. The molecular formula of (B) indicates that tt should
be benzoic acid and cornpound {A) should. th e refore, be a .
monosubstituted aromaUc n1ethyl ketone . The n10IccuJar formulaof :
(A) indicates that jt should be phenyl n1cthyl ketone (ac-ctophenonr). ;
Reactions are as foJlows: ·
0
II
C
a 'cH, +
(A)
2, 4-Dinltrophenylhydraztnc
2. 4 -0NP denvaUV~
1~mis try ,... .....fl
8. lnt<!xt l uestwtts
12.4 Arrange the following con1pounds in increasing order of their reactivity in
nucleophilic addition reactions.
(i) Ethanal. Propanal. Propanone, Butanone.
::.:, S.::-'..za}dehyde. p-Tolualdrhydr . p-Nitrobenzaldehyde. Acetophenone.
Hine: Consider steric effect and electronic effect.
12.5 Predict the products of the follo,vin~ reactions:
~+o
(i) _J ~ HO- NHl H' )
(U) r"l'70 0,)-=
V + NHi-NH ~ N OJ
)
0
II 1r
(ill) R-CH=CH-CHO + NH.,-C-NH-NH1
)
0
II
(i·)
~'Clll + Cl CCIl:.1NlIJ
1r )
9. .. ~ ,
l ~.•; r ; : l ,
l'h
, t r I ,t"
1 f ,
'. I
~
/ _
,/
,t
~ 11 q
(
, f ,.
·
:?'
I
, I
/
,,
.,,
J
10. Write chemical reactions to affect the following transformations:
(i) Butan-1-ol to butanoic acid
, (ii) Benzyl alcohol to phenylethanoic acid
lI (iii) ;3-Nitrobromobenzene to 3-nitrobenzoic acid
(iv) 4-Methylacetophenone to benzene-1,4-dicarboxylic acid
1 (v) Cyclohexene to hexane- I,6-dioic acid
; (vi) Butanal to butanoic acid.
f.
&n!"Ple •~
11. Chemistry
(i)
Cr0 ,- 11,SO,
CH,CH,CHlCll,Oll Joni's reagrnt
Butan-1-ol
M~
ether
3-Nltrobromobenzene
0-
~o
C
"-
0 2
N OH
3-Nttrobenzot
cactd
COCH ,VCOOK
.
,v, > ctU.H
1
so
1
I .,.
(._. ' KMnO.fKOH j ~ j}COOlf
H,C KOOC ~ Jooc ~
(v)
4-Methylacetophenone
0
Cyclohexenc
Butanal
KMnO,-H2SO,
Heat
esticm
Dlpotasslum benzene-
! . 4-dicarboxylate
OOOH
OOH
Benzene- I, 4-dlcarboxylic
acid
[ferephthallc acid)
Hexane- I. 6-dlolc acid (Adtplc acid)
Butanolc acid
Show how each of the following compounds can be i
converted to benzoic acid. I
(i) Ethylbenzene (11) Acetophenone
(lli) Bromobenzene (iv) Ph~nylethene (Styrentl
12. Itttext
12.8
uestio»
Which acid of each pair shown here would you expect to be stranger?
(i) CH
3
CO2
H or C~FCO2
H (ii) CH2FCO2H or CH ClCO H .
2 2
(ill) CH2
FCH2
CH2
CO2
H or CH3CHFCH2CO2H
[iv) F3
C -0-COOH or H3C O COOH
13. 12.1
12.2
12.3
12.4
t ~~rciscs
What is meant by the folloWing tem1s ? Give a n exa mple of the rea ction in
each case.
(ii) Acetal
(i) Cyanohydrin
(iv) Aldol (v) Hemiacetal
(iii) Semicarbazone
(vi) Oxime
(vii) Ketal (vii) lmine (ix) 2,4-DNP-derivative
(x) Schiff's base
Name the following compounds
(i} CH3 CH(CH:JCH2 CH2CHO
according to IUPAC system of nomenclature:
(ii) CH3 CH2COCH(C2H5)CH2CH2Cl
(ill) CH3 CH=CHCHO
(v) CH3 CH(CH:JCH2C(CH3 bCOCH3
(vii) OHCC6 H4 CHO-p
Draw the structures of the following
(i) 3-Methylbutanal
(ill) p-Methylbenzaldehyde
(v) 4-Chloropentan-2-one
(vii} p,p'-Dihydroxybenzophenone
(iv) CH3 COCH2 COCH3
(vi) (CH3) 3CCH2COOH
compounds.
(ii) p-Nitropropiophenone
(iv) 4-Methylpent-3-en-2-one
(vi) 3-Bromo-4-phenylpentanoic acid
(viii) Hex-2-en-4-ynoic acid
Write the IUPAC names of the following ketones and aldehydes. Wherever
possible, give also common names.
(i) CH3 CO(CHJ4CH3
(iii) CH3 (CHJ5 CHO
~CHO
(v) _J
...
(ii) CH3 CH2CHBrCH2CH(CH3)CHO
(iv) Ph-CH=CH-CHO
(vi) PhCOPh
12.5 Draw structures of the following derivatives.
(i) The 2.4-dinitrophenylhydrazone of benzaldehyde
(ii) Cyclopropanone oxime
(iii) Acetaldehydedimethylacetal
(iv) The semicarbazone of cyclobutanone
(v) The ethylene ketal of hexan-3-one
(vi) The methyl hemiacetal of formaldehyde
Aldehydes. Ketones and Carboxvl
14. Predict the products formed when cyclohexanera rbaJcteh
Y
derea
following reagmts. • e1
sI·
(I) PhMgBr and then HJO (II) Tollcns· r 1
1h
(Ill) Semlcarbazlde and weak acid Iv) Excrss C
lhano1
( eagen1
(v) Zinc amalgam and dllute hydrochloric acid and aetQ
Which of the follo1ng compo~nds would undergo aldol condensatt
the Cannizzaro reaction and wluch neither? Write the structures of t 0n, rlue
products of aldol condensation and Cannizzaro reactton. he e)(J)eet~~
(
I) Methanal (II) 2-Methylpentanal (Iii) BenzaJct h .
(iv) Benzophenone (v) Cyc o exanone vi) l-Pheny1
I h ( e Yde
(vii) Phenylacetaldehyde (viii) Butan-l-ol (ix) 2,2•Dirne~~0Panone
12.8 How will you convert ethanal Into the following compounds? Ylbutanai
(!) Butane 1.3-diol (Ill But-2-enal (ill) But-2-enoic acict t
Write structural formulas and names of four possible aldol co d
products from propanal and butanal. In each case, indicate Whtc~ ensatton
acts as nucleophile and which as electrophlle. aldehyde
1
. d C<>nnl-~- tl ' enva0v
12 10 An organic compound with the molecular formula CJI100 fonns 2 4-DNp d
1
reduces Tollens' reagent and un ergoes "-'UULJ..d.10 reac on. On vigorous OlCld e,
It gives 1,2-benzeneclicarboxylic acid. Identify the compound. atlon, !
12.11 An organic compound (Al (molecular formula CsH1sO:J was hydrolysed ,
dilute sulphuric acid to give a carboxylic acid (Bl and an alcohol (CJ. OXJcta~~ i
of (C) with chromic acid produced (B). (C) on dehydration gives but-I-en: ·
Write equations for the reactions involved. · ,
12.12 Arrange the following compounds in increasing order of their property as Indicated: r
(I) Acetaldehyde, Acetone. Di -tert-butyl ketone, Methyl tert-butyl ket I
)
one .
(reactivity towards HCN t
(ill CH3
CH2CH(Br)COOH, CH3CH(Br)CH2COOH, (CH:ihCHCOOH, .
CH3CH2CH2
COOH (acid strength)
(ill) Benzotc acid, 4-Nltrobenzoic acid, 3,4-Dinitrobenzoic acid,
4-Methoxybenzoic acid (acid strength)
12.13 Give simple chemical tests to distinguish between the following pairs ofcompounds.I
(1) Propanal and Propanone (ii) Acetophenone and Benzophenone !
(ill) Phenol and Benzolc acid (iv) Benzoic acid and Ethyl benwate
(v) Pentan-2-one and Pentan-3-one (vi) Benzaldehyde and Acetophenone
(vU) Ethanal and Propanal
12.14 How will you prepare the following compounds from benzene? You may use:
any inorganic reagent and any organic reagent having not more than ont
carbon atom
• (1) Methyl benzoate
(ill) p-Nttrobenzoic acid (11) m-Nitrobenzotc actd
(Iv) Phenylacetic acid
(v) p-Nltrobenzaldehyde.
12.15 How will you bring about the folllJwtng conversions 1n not more than two steps?
(1) Propanone to Propene (U) Benzotc acid to Ben:zaldehyde
UH) Ethanol to 3-Hydroxybutanal (iv) Benzene to m-Nltroacetophenonr
(v) Benzaldehyde to Benzophenone (vt) Bromobenzene to 1-Phenytethano
{vii) Benzaldehyde to 3-Phenylpropan-1-ol
(vlU) Benazatdehyde to a-Hydroxyphenylacettc acid
(ix) Benzotc acid to m- NitrobenzyI alcohol
12.16 Descrtbe the followtng:
~ (1) AcetylaUon
(ill) Cross aldol condensatton (U) CannJzzaro reaction
(tv) Decarboxylauon
15. each synthesis b y giving missin g s t arting mat<:rl.l, n·.i~n1 or µ, 1J<l11c1"'
1ete
coit'P cH Cl-l3 ( XCOOH
J,.,1 ~ ' KMnO. (ii) I ✓.:::, ~OCI,
(I} u KOH. heat COOH heat
H~CONHNH,
dil.NaOH
b.
0~
(iv) .,,~
O CHO NaCN / HCI
(vi)
COOH
(1) NaBH ,
(viii) CH3COCH2COOC,H.
{ii) H
Q-cHO
8 Gtve plausible explanation for each of the following:
12
'
1
(l) Cyclohexanone forms cyanohydrtn in good yield but 2.2.6-trtmethylcyclo-
hexanone does not. .
(ii) There are two -NH2 groups in sernicarbazide. However. only one is involved
in the formation of semicarbazones.
(iii) During the preparation of esters from a carboxylic acid and an alcohol in
the presence of an acid catalyst, the water or the ester should be removed
as soon as tt is formed
12.19 An organic compound contains 69.77% carbon. 11.63% hydrogen and rest oxygen.
The molecular mass of the compound is 86. It does not reduce Tollens· reagent
but forms an addition compound with sodium hydrogensulphite and give positive
iodofonn test. On vigorous oxidation it gives ethanoic and propanoic acid. Wrtte
the possible structure of the compound.
12
·20 Although phenoxide ion has more number of resonating structures than
carboxylate ton carboxylic acid is a stronger acid than phenol. Why?
12.1
Answers to Some lnten Questions
CHsO 0
I 11 ·
(i) HsC-CH-C-H
OH O
(U) li,C~H-C"2-1!-H
WI) Q-cHo
OH
0
II
(iv) CH3-C-CH2-CH2-CHO
CH3 0 CH3
(v) CH3CH}:ttJLtH-CH2CH,
0
-0-
11
(vij F C-CH3
